Electromagnetic relay



July 3, 1945. Y A. wELLMAN 2,379,772

ELECTROMAGNETIC RELAY F'1ed Sept. 2, 1943 Inventor: Albert, Wellman,

)0 5 .Wa/uff. x/

His Attornebg.

Patented July 3, 1945 issn 2,379,772 .ELECTRDMAGNETIC RELAY AlbertWellman, Scotia, N. Y., assignorto General Electric Company, Yacorporation of New York Application September 2, 1943, Serial No.500,992l (Cl. 20G- 111) fi Claims.

My invention relates to electromagnetic relays, particularly to totallyenclosed solenoid type relays, and has for its object the provision of anew and improved relay of thistype characterized particularly byreliability in operation and simplicity of assembly and disassembly.Such a relay is low in cost and adapted for quick, easy and inexpensivemanufacture in large quantities.

According to my invention, all the parts of both the magnetic andelectrical circuits are held in operative relation solelyby the closuremembers of an outer insulating` casing.

The novel features which are characteristic of my invention will be setforth with particularity in the claims appended hereto. The inventionwill be better understood, however, and its objects and advantages morefully appreciated by referring first to the following detailedspecification taken in conjunction with the accompanying drawing inwhich Fig. 1 is a plan view of one end of a relay embodying myinvention; Fig. 2 is a cross-sectional view taken along the line 2-2 ofFig. k1; Fig. V3 is a plan view of the opposite end of the relay withthe enclosing cover removed; and Fig. 4 is an exploded perspective viewof the entire relay.

Referring now to the drawing, I have shown an electromagnetic relaycomprising a cylindrical venclosing casing I 0, preferably formed of asuitable non-magnetic electrically insulating material, vand having anexternal peripheral shoulder I I slightly spaced from one end thereof.Between the peripheral shoulder II and the adjacent end of the .casingI0, thel casing I0 is of somewhat reduced external and internaldiamevter thereby to providel an internal peripheral shoulder II a insubstantially l the same plane as the shoulder II, 'I'he reduced sectionof the casing Ill is provided with two pairs of diametrically disposedlongitudinal slots I2 and I3. As shown at Fig. 2, the internal shoulderIIa is cut away above the slots I2 and I3 to provide internallongitudinal recesses I Ib for a purpose which will appear more fullyhereinafter. The peripheral shoulder II is cut away at diametricallyoppo' site points I5.

I8 is provided internally with a hollow cylindrical boss I9 for apurpose which will be more fully described hereinafter.

Removably disposed within the casing Ill is a metallic liner 20 ofmagnetizable material having at one end a pair of diametrically disposedlongitudinal slots 2 If A pair of diametrically op..

posite bosses 20a, on the liner 20 are 'arranged for at diametricallyopposite points, ya pair of off-set terminal connectors 23.` In theassembled position shown at Fig. 2, the terminal connectors are soarranged that their off-set portions overlie the shoulders is at thebases of the slots I4 in the casing I0. In this position, the terminalconnectors 23 do not interfere with the threaded engagement of the endcap I1 within the casing I0, but their radially extending outer ends arefirmly clamped between the end cap I1 andthe shoulders I6.

Between the upper end of the energizing coil 22, as viewed in thedrawing, and the upper e'nd cap. I1 is disposed a metallic disk 24 ofmagnetizable material having at the center thereof a hollow cylindricalboss 26 arranged to exten-d a short distance longitudinally into thecoil 22. The hollow boss 26 is lined With a cup-shaped liner 21,preferably formed of a non-magnetizable metal characterized by longwearing qualities. The vcup-shaped liner 21 provides a permanent air gapand` also serves slidably to supporta magnetizable plunger 28 whichextends into the coil 22 andis provided with a conical face 29. Toprevent the formation of an air cushion between the plunger 28 and liner2J, the base of the liner 21 is apertured at 21a and the end cap I 1 isformed witha circular linternal boss I1a thereby.

AThe opposite endAof the casing is provided with one pairofdiametrically disposed longitudinal slots I4. The slots I4 extendfarther longitudinally on the outer surface of the casing than on theinner surface, thereby to provide a pair of shoulders I6 at the bases.0f theseslots. Opposite ends of the cylindrical casing yIl) arethreaded to receive apair of end caps I1 and I8, preferably formed ofthe samemon-magnetic electrically in; suhting material as the casing I0.l'I'he end caps Il and I8 are generallycupfshped and thecat'4 to providea small air -space I1b between the disk 24A` and the end cap I1. Sincethe liner 2" constitutes. a necessary and permanent air sali or'break inthe magnetic circuit, its reluctance' is minimized byforming the linerto present .a large area for the .passage of magnetic iiux` be-V tweenthe plunger. 28 and the end cap 24.

It will be noted that the portion of the plungerv 28 Vwhich slideswithin the liner 21 is of smaller diameter than the plunger head.` Thisreduction of the plunger diameter makes possible the large flux areathrough the hner 21. It should be notedl B5' that leakage :dux betweenthe lower end of the' cylindrical .has 26 and the plunger head providesa hold-out force which must be minimised.

' ing portions for these strips.

Such forceis satisfactorily reduced by making the minimum length of thisleakage flux path at least two or three times the length of the air gapthrough the liner 21.

Extending into lthe coil 22 from the opposite end thereof I provide amagnetizable core member 30 having a reentrant conical face 3| for cooperation with the conical face 29 of the plunger 28. The core 3D ismounted at its other end upon a magnetizable disk 32 which extendsacross the lower end of the coil 22 between the stationary core portion3D and the magnetizable liner 20, thereby to complete a magnetizableframe for the relay.

The stationary core 30 and the magnetizable end disk 32 are centrallybored along the longitudinal axis of the core 30 slidably to receive anactuating pin 33 which is preferably formed of non-magnetizablematerial. The pin 33 extends beyond both ends of the magnetizable core30, the upper end of the pin having a reduced end portion 34 iittinginto a bore in the end of the movable plunger 28. The lower end of thepin 33 has a reduced end portion 35 which fits snugly into a knob 36having a peripheral shoulder 31 at the upper end thereof. Beneath themagnetic disk 32, and seated upon the internal shoulder Ila of thecasing Ill, I provide an insulating disk or washer 3B. the casing intoan upper coil compartment and a lower contact compartment. The partsthus far described in the coil compartment are all clamped in operativerelation between the shoulder Ila and the upper end cap |1. Theactuating pin 33 passes slidably through the washer 33 so that the knob36 lies in the lower or contact compartment.

Referring now to the lower end of the relay, as viewed in the drawing,there are radially disposed within the pairs of diametrical slots l2 andI3 two pairs of contact strips 39 and 40. Each contact strip 39 is ilatand is provided internally and externally with keying portions toprevent radial displacement of the strip with respect to the casing, l0.The strips 39 are enlarged both internally and externally to key thestrips against radial displacement, the internal enlargements serving asxed contact surfaces and the external enlargements serving as terminalconnectors. The Contact strips 40 are ofi`- set so that their inner andouter portions lie in different planes. The outer portions only of thecontact strips 4|) are enlarged to provide terminal connections andkeying connection with the slots I2. These outer portions of the strips40 lie against the lower surface ofthe external peripheral shoulder onthe casing and in the same plane as the outer portions of the contactstrips 39. Within the slots |2, however, the contact strips 40 areoff-set and extend a small distance longitudinally of the casing i0. Theoif-set in the contact strips 40 serves both to dispose the inner endsof the contact strips 40 in a plane displaced from the plane of theinner ends of the contact strips 39, and also as a key to preventoutward radial displacement of the contact strips 40 with respect to thecasing |IJ. Because of the ofl-set in the contact strips 40, it isunnecessary to provide enlarged inner key- The contact strips 40, likethe contact strips 39, serve the dual pur`- pose of providing at theirinner ends xed contact surfaces and at their outerends terminalconnectors. Both pairs of contact strips 39 and 40 are clamped firmly inplace, in the assembled The washer 38 eiectively divides position of therelay, between the end cap IB.

and the lower surface of the external peripheral shoulder on the casingl0.

Referring now particularly to Figs. 2 and 3, it may be observed that4 Iprovide between the planes of the contact strips 39 and the inner endsof the contact strips 4D an S-shaped movable contact element 4|. Thecontact element 4| is preferably formed of electrically conductingspring material and comprises a diametrical member having a hole at thecenter thereof and arcuate portions extending oppositely from the endsthereof. vIt will be observed from Figs. 2 and 3 that the movablecontact member 4| is mounted upon the collar 36 in such a position thatthe diametrical body portion of the contact member serves as a bridgingcontact between the fixed contact strips 39 and the arcuate extensionsof the member 4| are disposed to engage the fixed contact strips 40. Toopposite ends of the, movable contact member 4| are attached a pair ofmoving contacts 4|a and lib, which, in operative position, extend asmall distance into the internal recesses lib to limit rotation of thecontact member 4| with respect to the casing l0 thereby to maintain themoving contacts in proper alignment with the xed contacts.

The movable contact member 4| is biased upwardly and into engagementwith the shoulder 3T on the knob 36 by means of a helical compressionspring 42 which is seated at one end inthe hollow cylindrical boss i9 ofthe end cap |8 and the other end of which holds the Contact member 4|against the shoulder 31. The spring 42 biases the moving contact member4| and actuating pin 33 upwardly, as viewed in the drawing, so that themember 4| normally engages the fixed contact strips 40. In this positionthe movable plunger 28 is also held spaced from the magnetizable core3U.

In operation, the movable bridging Contact 4l normally completes acircuit `between the fixed contact members 40. The contact 4| is movablebetween the xed contacts 40 and the xed contacts 39, the fixed contacts39 being shown in the drawing below the movable contact mem ber. Thus,when the actuating coil 22 is energized, the movable plunger 28 is drawndownwardly into engagement with the magnetizable core 30 and presses theactuating pin 33 downwardly against the bias of the compressionengagement with the normally open xed contacts 39.

To facilitate mounting of my relay upon any suitable base, which may bea vertical or horizontal surface, I provide a mounting bracket 43encircling the casing I0 and having a pair ol attachment feet extendingthrough the cutaway portions |5 of the shoulder The bracket 43 is formedof spring material and is slightly bent diametrically at 43a to providesome resilience in the mounting.

In View of the foregoing detailed explanation of the structure andarrangement of the various parts of my relay, it will now be evidentthat all parts of my relay are readily accessible and that the whole issimply and easily assembled or disits legs passed through the cutawaysections I of the shoulder Il. The insulating disk 38' is then slippedintothe casing from the upper en'd and placed against the internalperipheral shoulder ila in the casing. The connected'disk 32 and core 3|are lthen slipped into thcasing on top of the insulating disk 38.

` upside down, the actuating pin 33, with the knob attached, may beplaced in the core and the movable contact member 4| slipped over theend of the knobI 36 and against the shoulder lll'. 'lhe pairs ofstationary contacts 39 and W are now slipped longitudinally into theirrespective pairs oi slots I3 and I2, the inner ends of the contactsu 40being placed under the contact member di 4and `the inner ends of thecontacts d@ being placed over the member Il. Finally, the helicalcompression spring I2 is placed in the boss i9, where it is frctionallyheld sufilciently to permit it to be inverted over the end oi the lrnob36, and the end cap I8 is screwed in place to clamp the iixed contacts39 and 40 Next, the liner 2@ may be placed in the casingand the slotsmagnetic insulating material attached to opposite ends of said casing toclose said compartments and to hold the parts of said relay in fixedoperative relation, and a compression spring interposed between thecontact compartment closure cap and said movable contact member, saidcontact compartment closure cap clamping said iixed contacts in fixedposition against said external casing shoulder.

2.11m electromagnetic relay comprising an open-ended cylindrical casingof non-magnetic insulating material having a peripheral shoulder axiallyspaced from one lend thereof, said casing being slotted longitudinallybetween said peripheral .shoulder and said one end, an energizing coildisposed within said casing, a plunger movable axially of said casingwithin said coil, a movable contact member operatively connected torsaid plunger, a contact strip extending radially through said slot andhaving keying portions internally and externally of said casing,

and an end cap of non-magnetic insulating material -threadedly engagingsaid one end of said in their operative positions. The relay is nowtotally enclosed, substantially dustproof and waterproof, and may ifdesired be hermetically sealed. Finally, the relay may be mounted uponany suitable base by means of the mounting bracket 43.

While l have described only one preferred embodiment of my invention byway of illustration, many modications will occur to those skilled in theart and I therefore wish to have it understood that I intend in theappended claims to cover all such modifications as fall within the truespirit and scope of my invention.

What I claim as new and desire Ito secure by Letters'Patent `of theUnited States is:

1. An electromagnetic relay comprising an open-ended cylindrical casingof non-magnetic insulating material provided with internal and externalperipheral shoulders adjacent one end, said casing being slottedlongitudinally at diametrically opposite points between said one end andsaid shoulders, an insulating washer seated on said internal shoulder todivide said casing into coil and contact compartments, a removablecylindrical liner of magnetizable material disposed within said coilcompartment, a removable cylindrical energizing coil disposed withinsaid liner, a magnetizable core centrally positioned in said coil andextending from said washer partially through said coil, a magnetizableplunger within said coil movable longitudinally into and out ofengagement with said core, a pair of magnetizable disk-s disposed atopposite ends of said coil to complete a magnetic frame for said relay,one of said disks being attached to one end of said core and the otherof said disks slidably receiving one end of said plunger, a pair ofiixed contacts extending radially through the longitudinal slots of saidcasing into said contact compartment, a sldable actuating rod extendingfrom said plunger through said core and into said contact compartment,n. movable contact member mounted upon the extending end of said rod, apair of end caps of noncasing lto close said casing and to clamp saidcontact strip between said cap and said shoul-A der, whereby the innerend of said strip provides a fixed contact surface and the outer end lofsaid.

strip provides a terminal connector.

3. An electromagnetic relay comprising an open-ended cylindrical casingof non-magnetic insulating material having a peripheral shoulder axiallyspaced from one end thereof, said casing being slotted longitudinally atdiametrically opposite points between said peripheral shoulder and saidone end, an energizing coil disposed within said casing, a plungermovable axially of said casing within said coil, a movable bridgingcontact operatively connected to said plunger, a contact strip extendingradially through each of said slots and having keying portionsinternally and externally of said casing, and an end cap of non-magneticinsulating material threadedly engaging said one end of said casing toclose said casing and to clamp said contact strips between said cap andsaid shoulder, whereby the innerends of said strips provide xed contactsurfaces and the outer ends of said strips provide terminal connectors.

4. An electromagnetic relay comprising an open-ended cylindrical casingof non-magnetic insulating material having internal and externalperipheral shoulders axially spaced from one end thereof, said casingbeing slotted longitudinally at diametrically opposite points betweensaid shoulders and said one end, an insulating washer] seated upon saidinternal shoulder to divide said casing into separate coil and contactcompartments, an energizing coil disposed within said coil compartment,a plunger movable axially of said casing within said coil, a movablebridging contact positioned in said contact compartment and operativelyconnected to said plunger, a pair oi' contact strips extending radiallythrough said slots and having keying portions internally and externallyof said casing, anend cap o! nonmagnetic insulating material threadedlyengaging said one end of said casing to close said. contact compartmentand to clamp said contact strips between said cap and said externalshoulder, and a compression spring seated ailainst said cap and engagingsaid bridging contact to bias said bridging contact to a normal positionwith respect Ito said xed contacts.

ALBERT wmmn,

